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### Author Topic: Hi Fellow CNC Enthusiasts  (Read 2651 times)

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#### Lance

• 4
##### Hi Fellow CNC Enthusiasts
« on: March 26, 2011, 11:57:03 PM »
I've just upgraded my Multicam router engraver (8ft x 4 ft) with Mach3 and am delighted with the result!
Am now trying to figure out "wrapping" using my 4th axis and would like to connect up with with other guys using similar set up.
My current frustration is trying to draw a wrap in V Carve pro - seems to be an issue getting the Z set right - have figured that the  cutting depth is homed at material centre (Y), but not getting a 360 degree wrap and in the  3D view. I'm having to set material thickness at half so only see half the material in 3D preview......Grrrrrr!
Also trying to figure out calibration of  4th axis - logic tells me it would have to work on degrees rather than a lineal measurement, but can't see how to do it.
Have been in the CNC  game for over 10 years and can see great benefit in sharing ideas etc. I operate a 3D signage manufacturing business here - shopfront signs, light boxes, engraved timber signs and so on.
Look forward to connecting up with similar 3D chomping operators around the world......Cheers!

#### Tweakie.CNC

• 7,903
• Super Kitty
##### Re: Hi Fellow CNC Enthusiasts
« Reply #1 on: March 27, 2011, 04:27:16 AM »
Hi Lance,

Welcome to the forum.

I wrote these notes on setting up a 4th axis some time back, don't know if it's any help.

For such purposes as cutting spur gears, machining splines or flats on round stock etc etc the position of the rotary axis is usually expressed in degrees. A GCode command such as G0 A10 will rotate the axis 10 degrees and so on. To set up the axis within Mach it is necessary to specify the ‘Steps Per’ (degree) and this is achieved by taking the steps of the stepper motor and multiplying by the micro stepping setting (if any) and then multiplying by the gear ratio then dividing the result by 360. In my case this is 200 (steps) x 8 (micro steps) x 60 (reduction ratio 60:1) / 360 (degrees) = 266.6666 steps per. Unimportant really but had I thought about this a bit more at the time I was cutting the worm gear for my rotary axis I would have made the reduction ratio 63:1, then I could have had a nice round figure for the steps per degree.

Angular mode is the most common and also the most useful way in which a rotary axis is used but there are alternatives….

When engraving on the surface of a cylinder, for example, it is convenient to have the rotary axis set for movement in mm but as this will vary, depending on the diameter of the work, there is a trick to getting it just right. One method for finding the ‘Steps Per’ is to calculate how many steps are necessary for the axis to complete one revolution and divide this figure by pi. In my case this is 200 (steps) x 8 (micro steps) x 60 (reduction ratio 60:1) / 3.142 (pi) = 30553.787 steps per to enter in Mach. Now this figure represents a linear movement of 1mm around the circumference of a 1mm diameter cylinder. In order that this can be used for any diameter of cylinder another calculation has to be performed and that is 1 divided by the diameter of the work (1/diameter). The result of this calculation is then entered into the rotary axis scale DRO within Mach. My version of Mach did not have an A axis scale DRO (like the X,Y &Z axis have) so this had to be added using Screen4 (which can be downloaded, free of charge, from the Artsoft website – For reference the A axis scale DRO is OEM Code 62 and it’s associated LED is OEM Code 44).
As an example, to engrave on the surface of an 80mm diameter cylinder it is 1 / 80 = 0.0125 so 0.0125 is entered in the A axis scale DRO now a GCode command of G0 A10 will rotate the axis so that the surface of the 80mm diameter work rotates 10mm. Using this method means that simple, conventional, engraving programs and existing GCode programs can be used for engraving onto curved surfaces such as tumblers, cups etc.
Although perhaps not quite as accurate as when the axis has been set up for angular movement in the first place - entering pi / 360 or 0.00873 into the A axis scale DRO will allow the axis to then operate in degrees ie. G0 A10 will rotate the axis 10 degrees.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

#### Lance

• 4
##### Re: Hi Fellow CNC Enthusiasts
« Reply #2 on: March 27, 2011, 07:58:45 PM »
Many thanks Tweakie
Yes - the info was helpfull as it gave me a clearer understanding on how these things are programmed.
Have a hunch Mach 3 can do all the calculations for me as is designed for other machines aside from router tables - such as lathes etc - it's a case of finding out how it works!
I tried setting up another profile for wrapping only, but all the changes I did there reflected back into my router table profile....grrr!

Cheers
Lance

#### ger21

• 6,288
##### Re: Hi Fellow CNC Enthusiasts
« Reply #3 on: March 27, 2011, 08:14:21 PM »
Vectric has a forum section specifically for wrapping at their site.
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html

#### Greolt

• 956
##### Re: Hi Fellow CNC Enthusiasts
« Reply #4 on: March 27, 2011, 08:26:55 PM »
Be a good idea to ask Vcarve Pro wrapping questions on the Vectric forum.

http://www.vectric.com/forum/

Because you can upload the .crv file, and experienced users can take a look at it.

Not that good help is not available here, it certainly is, but there you will get a concentration of Vectric users who are using the wrapping PP.

Greg